A Stanford study shows that exposure to criminal-justice inequality makes white subjects more likely to support harsh policies.

A new study suggests that white people support harsher criminal laws if they believe more black people are incarcerated, reports ThinkProgress.

Rebecca Hetey and Jennifer Eberhardt of Stanford University’s psychology department conducted the study, in which white subjects watched two videos of mug shots. One video showed mug shots in which 25 percent were those of black men. In the other video, nearly half of the mug shots were those of black men. After watching the videos, the subjects were given the option to sign a petition to reform California’s harsh sentencing laws.

The study found that “over half of the participants who’d seen the mug shots with fewer black men signed the petition, whereas only 27 percent of people who viewed the mug shots containing a higher percentage of black inmates agreed to sign.”

“Many legal advocates and social activists seem to assume that bombarding the public with images, statistics and other evidence of racial disparities will motivate people to join the cause and fight inequality. But we found that, ironically, exposure to extreme racial disparities may make the public less, and not more, responsive to attempts to lessen the severity of policies that help maintain those disparities,” Hetey noted.